In general, thermoplastic copolyester resins have excellent flexibility and weather resistance and also exhibit excellent adhesion to various substrates and therefore, they are widely used as paints or adhesives. It is known that they exhibit excellent adhesion, in particular, to synthetic resins containing polar groups, such as soft or hard polyvinyl chloride resins, polyester resins, polycarbonate resins, ABS resins, and polyurethane resins. On the contrary, they exhibit no adhesion to polyolefin synthetic resins. It is also known that they exhibit adhesion to metals such as aluminum, lead, iron, and copper, but their adhesion is not always satisfactory as compared with that to synthetic resins containing polar groups such as polyvinyl chloride resins.
Another problem of the thermoplastic copolyester resins is that when they are used as adhesives to various substrates, their adhesive strength between the layers of the resulting laminated article decreases with a lapse of time because reduction in molecular weight occurs due to hydrolysis. Thus, laminated articles of synthetic resins and/or metals as produced using the above thermoplastic copolyester resins alone as adhesives are not sufficiently satisfactory in respect to adhesion from the practical viewpoint.
It has therefore been desired to develop resins exhibiting good adhesion to all kinds of substrates and also having adhesive durability against moisture, with the both being well balanced.
Still another problem of the thermoplastic copolyester resins is that their fabrication property is poor. That is, in laminating the polyester resins on substrates such as films and metals by commonly used fabrication techniques such as inflation, T-die extrusion, extrusion lamination, and coextrusion, they stick on and attach to a cooling roll and cannot be separated therefrom, which makes the fabrication impossible. Even if the fabrication is performed when the resulting film is once wound in the form of a coil and then is intended to again produce laminated articles by the off-line system, difficulties are encountered in unwinding because of blocking. Thus, the fabrication property is still poor. It has therefore been desired to develop resins which have excellent fabrication property and cause less film blocking.